Absolutely happy so far.
I don’t think I’ve ever had a smoother transition between versions. So far everything loaded just great. The new way to install the license worked perfect. It didn’t mess with anything in 10.5. It copied all of my setting over and key commands. I’m glad I didn’t see it for a few days because the traffic on the net was less. Price is more than fair for me.
Thanks to all that worked on the upgrade. Sure gave me an early holiday present.
Now let me upgrade steinberg lol
Extremely happy on Mac, excellent upgrade!
After all the update hassle, I still must say I’m quite pleased with C11!
Stability about the same as C10.5.20, which I never had any problems with.
So far only small graphical glitches here and there, but for a .0 release not bad!
Also a couple of useful features added… I’d give this release 8/10. 
So worth it then? I usually get the updates immediately but waited this time because of the problems and now wondering if it’s worth waiting until 11.5 since as far as I can see this is not a major update and I’m not sure it will benefit me. I hear things about problems with graphics but on 10.5 I haven’t noticed anything. I run on a 4K monitor and 100% so I don’t use scaling. Never even thought about it before but this time I’m a little reticent.
I’ve used it since day 1(which is not very long, 4 days), and it is surprisingly stable for a .0 version. 10.5 was terrible at first, 11.0 is usable.
Great thing is, you can keep your previous version. Don’t like it? Bugs? Go back to your previous version.
This has been my experience. Export and midi tools (curve) worth the upgrade alone. Seems rock solid. marginal - if any ASIO improvement. I am ok as long as not step back there.
If you are on a Mac it is worth it for the smooth scrolling. The key editor scale updates are great as well. There are other things I would have liked to see, but overall worth it especially for those two. Icing on the cake is SpectraLayers for spectral editing, which is ARA so you can use it in other DAWs. I like Supervision and Squasher, although I have other plugins that handle what they do.
Long term user, very happy solid and a decent improvement
Had it a few days now with no problems…liking it a lot, old projects loading without issue, installed very easily… 
On 11 and very happy with it. One crash on exit after using it for 8 hours or so in total. Enjoying the key editor tweaks. The way 11 defaults to the minimum height that note names can be displayed at is very nice. Am on Mac, but personally I haven’t noticed any UI performance change.
I am using 11 for several days now, and so far everything seems to work fine. No crashes or hangs on exit (well I never had that anyway), and all the 3th party plugins I use seem to work fine. Of course only several days is not that long, but I feel confident enough to do some small projects with it. The bigger and more critical projects will get tested, but remain on the older version until the new version had a long enough duration test.
So far so good, Works just fine in a 9 year old PC with W10 20H2 now, Firewire interface and since C11+ newest W10 somewhat less CPU usage.
The new features of C11 (for me the EQ + Squasher the most) are great.
Not the greatest update for me personally. Wish they adding some other features but o well. I can say this it is very smooth on my Mac. The scrolling alone is a big plus. Zooming in and out horizontal is still to fast but vertical scrolling is much better now.
Talking about scrolling up and down from track to track.
A few strange behaviors initially when loading old projects but this was sorted. Not sure why but for me there always seems to be a break in period with a new Cubase version, as if it needs to adjust itself to a new environment. The Offline Processing is finally working for me, too, this is a big plus because it has never worked properly with my iZotope plugs before now. It’s actually quite amazing to use it as it was intended. The scaling deal is not perfect, I had to go back to 100% vs. 125% but I’ll live. Complex projects load and close faster, as well. Overall I feel it is definitely BETTER than C10 or C10.5. I’m happy.
Thanks to all for the great responses. I pushased yesterday and will download and install tomorrw… I will post my results and do a quite session…
Didn´t really update to 10.5, subjectively it wasn´t worth full price. 11 for me is, running with great elegance on Mojave. I also concider this as a investment into their remote controller system overhaul in future( i´ll admit i´m not fully informed about that but looks game changer by a few looks)
Installed without a problem all of my settings so far are there…
Yes 9 days later and still going strong , had a few crashes but that seems to be windows not supporting Firewire any more but once i reinstalled the legacy 8.1 driver every thing is really stable , love all the new features and my fav is defo the rehashed sample track